Plastic containers are easy to form, can be inexpensively produced and have, therefore, been widely used in a variety of applications. Specifically, an olefin resin container of the shape of a bottle of which the inner wall surface is formed by using an olefin resin such as low-density polyethylene and which is formed by direct blow-forming, has been desirably used as a container for containing viscous slurry-like or paste-like contents such as mayonnaise and ketchup from such a standpoint that the content can be easily squeezed out.
However, the above viscous content tends to adhere and remain on the inner surface of the container and it is difficult to use the content filled in the container up to its last drip. Namely, this kind of problem occurs due to lack of slide-down property on the inner surface of the container for the viscous content.
As a container that meets the above requirement, a patent document 1, for example, is proposing a bottle of a multilayered structure including an innermost layer of an olefin resin that has an MFR (melt flow rate) of not less than 10 g/10 min.
The bottle of the multilayered structure includes the innermost layer that has excellent wettability to the oily content. Therefore, if the bottle is inverted or is tilted, then the oily content such as mayonnaise or the like falls down spreading along the surface of the innermost layer and can be completely discharged without adhering or remaining on the inner wall surface of the bottle (on the surface of the innermost layer).
As for the bottles for containing viscous non-oily contents in which plant fibers are dispersed in water like ketchup, a patent document 2 and a patent document 3 are proposing polyolefin resin bottles having an innermost layer which is blended with a saturated or unsaturated aliphatic amide as a lubricating agent.
The above patent documents 1 to 3 are all trying to improve slipping property of the plastic containers for the contents based on the chemical compositions of the thermoplastic resin compositions forming the inner surfaces of the containers, and are achieving improvements in the slipping property to some extent. However, limitation is imposed on improving the slipping property due to limitation on the kinds of the thermoplastic resins that are used and on the additives, and striking improvement has not been achieved yet.
On the other hand, a patent document 4 is proposing a packing material comprising a composition that contains an additive having an HLB of not more than 5.0 in an amount in a range of 0.3 to 3 parts by weight per 100 parts by weight of the polyolefin resin.
Further, the present applicant has previously proposed a container of which the inner surface or the surface that comes in contact with the content is a liquid permeable surface and which is holding a liquid in the liquid permeable surface (Japanese Patent Application No. 2012-199236) and a container of which the inner surface is formed by using a resin composition that contains a resin for forming and a liquid (liquid immiscible with the content (Japanese Patent Application No. 2013-23468). These containers are forming a liquid film at portions that come in contact with the content, and exhibit very improved slipping property for the fluid contents such as ketchup, sauce, mayonnaise and the like.
However, these containers are still accompanied by a problem in regard to stably holding the liquid film that is formed to improve slipping property for the content, and further improvements are necessary.